Setup LXD based on a feature pull request

This guide details the steps for setting up lxd your lxd build based on a feature pull request that is not yet released via snapd.

1. Make sure you have lxd snap installed, if not, refer to HACKING.md for instructions.
2. Create and launch a container instance with ubuntu:22.04, name it builder or something suitable. The container will be used to compile lxd and lxc binaries and will ensure that dependencies are the same as those used in the published snaps.
3. Once the container is running, navigate to its terminal:

3.1 update and upgrade apt with:

apt update
apt -y upgrade

3.2 install package dependencies for lxd

apt -y install acl attr autoconf automake dnsmasq-base git libacl1-dev libcap-dev liblxc1 liblxc-dev libsqlite3-dev libtool libudev-dev liblz4-dev libuv1-dev make pkg-config rsync squashfs-tools tar tcl xz-utils ebtables
apt -y install lvm2 thin-provisioning-tools
apt -y install btrfs-progs
apt -y install curl gettext jq sqlite3 socat bind9-dnsutils
apt -y install shellcheck

3.3 install go

apt -y install snapd
snap install go --classic

3.4 clone the source code

git clone https://github.com/canonical/lxd
cd lxd

3.5 check out a specific pull request from the lxd repo. You will need the pull request id and replace pull_id in the command below

git fetch origin pull/[pull_id]/head:[branch_name] && git switch [branch_name]

3.6 build lxd dependencies, make sure you are inside the /lxd directory

make deps

3.7 at the end of step 3.6, there will be some instructions displayed in the shell output for setting up environment variables. Copy those and run them to set them up, an example is shown below:

export CGO_CFLAGS="-I/root/go/deps/raft/include/ -I/root/go/deps/dqlite/include/"
export CGO_LDFLAGS="-L/root/go/deps/raft/.libs -L/root/go/deps/dqlite/.libs/"
export LD_LIBRARY_PATH="/root/go/deps/raft/.libs/:/root/go/deps/dqlite/.libs/"
export CGO_LDFLAGS_ALLOW="(-Wl,-wrap,pthread_create)|(-Wl,-z,now)"

3.8 finally we can now build the lxd and lxc binaries, once done, exit the container

make
exit

4. Get the binaries from the container

lxc file pull builder/root/go/bin/lxd lxd.debug
lxc file pull builder/root/go/bin/lxc lxc.debug

5. Push the newly compiled binaries to your existing lxd snap working environment

sudo mv lx[cd].debug /var/snap/lxd/common

6. Restart lxd daemon, NB: note if the new binaries compiled includes feature changes that require a database schema change, then you will need to revert those database changes manually later when removing the debug binaries. Alternatively, you can also completely purge your local lxd snap installation and reinstall again.

sudo systemctl reload snap.lxd.daemon

7. Revert or purge if db schema changed

sudo rm /var/snap/lxd/common/lx[cd].debug
sudo systemctl reload snap.lxd.daemon

or

sudo snap remove --purge lxd